Pinpointing the Health Impacts of Urban Noise

Researcher Erica Walker wants to change the way cities think about their aural landscapes.

A taxi honks its horn. A delivery driver guides his noisy two-wheeled cart, stacked high with boxes, across the street. And underground, the subway rumbles. Erica Walker wants to capture it all.

For the past year, the Ph.D. candidate at Harvard’s T.H. Chan School of Public Health has been bicycling between Cambridge, Boston, and Somerville, Massachusetts, with a decibel meter. Her aim is to measure just how loud different neighborhoods, streets, even crosswalks are. At the same time, she asks residents to fill out surveys about the impact city noises have on their lives and sanity.

Walker, a Mississippi native with a background in math, economics, and furniture construction, will eventually co-analyze more than 900 surveys and 400 decibel readings to assign a noise value to individual homes. Her plan is to map perceived noise versus the reality in a handful of neighborhoods, and then measure those noise levels against certain health outcomes like cardiovascular disease.

“Noise is insidious,” she says. “It affects you acutely, but also long-term. This is something that people don’t really talk about, but something people really suffer from.”

Eventually, a noise value could be assigned to every residence in Boston.

What she’s already discovered is that low-frequency noise may be the most insidious. The subway train rolling underneath one’s feet; the airplane taking off; an idling diesel truck or city bus. These are the frequencies that are often more of a vibration than an audible sound, she says, “the type that rattles inside of my bones.”

Trouble is, those lowest decibel readings (along with the highest—think jackhammer or ambulance siren), are frequently discarded in noise studies, which tend to weigh only the mid-range levels that most people hear. Walker hypothesizes that this approach may not be painting the most accurate picture of how urban noise affects real people, which is why she’s using a wide variety of collection methods that factor in the full spectrum of noise readings.

“We shouldn’t just throw out components that we think they don’t hear, we should consider the whole spectrum,” Walker says. “And we should ask the community what they’re bothered by. If you’re going into a community and you’re monitoring noise, you need to ask them, what’s bothering you? Then you can make connections between noise and health.”

Which is why Walker has become such a voracious surveyor. She’s currently surveying in every Boston neighborhood, in multiple languages, asking residents to rank certain city noises—a car idling or subway rumbling, for instance—on a ten-point scale of how bothersome or stressful they are. She says she’s been surprised how many respondents are willing to complain while at the same time say they’ve gotten used to the noise around them. Still others, she says, are in denial that their neighborhoods have a noise problem.

When all the surveys are collected, Walker plans to create a “perceived noise map,” which compares the perceptions of Boston residents to the readings she’s taken with her decibel meter. Eventually, a noise value could be assigned to every residence in Boston.

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Walker’s research is in some ways a throwback to a golden era of noise research that reached its height in the U.S. in the 1970s, during the Nixon administration. The Noise Control Act of 1972 authorized the Environmental Protection Agency to study the effects of noise for the first time and set up the federal Office of Noise Abatement and Control.

“We now have the authority to come to grips with an environmental problem that affects millions of people,” then-EPA Administrator William D. Ruckelshaus said at the time.

Walker, with her decibel meter in the field. (Courtesy Emily Dubreuil)

Over roughly the next decade, several landmark epidemiological studies documented the human toll that noise—especially airplane noise—can take. Then came Ronald Reagan’s massive deregulation and dismantling of the Environmental Protection Agency. The federal noise abatement office closed in the early 1980s, and noise regulation returned to cities and states. With it went much of the funding for noise research, says David Sykes, who runs the nonprofit Acoustics Research Council, which focuses on policy-level analysis of noise issues. He expresses surprise and delight about Walker’s work in Boston.

“The fact that she’s actually doing an epidemiological study is very, very rare,” he says. “What she’s doing is very courageous. It’s not a path you would chase if you were trying to get a tenured appointment somewhere.”

In studying noise and its effects on people, Walker insists she’s discovered her academic “calling,” which she is prepared to follow as far as it will take her. It may soon lead her out of Boston to Brooklyn Heights, where lifelong New Yorkers Roberto Gautier and his wife, Elissa Descoteau, live in a 23rd-floor affordable condo on Cadman Plaza near the Brooklyn Bridge. There, the city has been rehabilitating the historic bridge for the past five years. So as not to disrupt daytime traffic across the historic span, construction clatter—the shrill beeps of construction vehicles backing up, the ting of steel striking steel, and even jackhammers—often begins at 11 p.m. and continues through the night.

Despite living in a city with a relatively strong history of noise abatementresearch and enforcement, Gautier and his neighbors say they are suffering mightily. They’ve taken their grievances to city officials but say they’ve seen little, if any, improvement. So he reached out to Walker when he heard she was studying the effects of low-frequency noise on human health—especially mental health.

Walker is making plans to take her decibel meter to Cadman Plaza. Gautier’s story is not unlike those Walker says she’s heard biking Boston’s neighborhoods and speaking with residents. Her hope is that her research, which she expects to wrap up this year, could bring the hum and din of city life back into conversations about public health.